1. Field of the Invention
The invention relates to control and operating systems for large commercial or institutional laundry installations generally employing three or more washing machines. In such installations, it is common to have a fairly large number of different chemicals which can be injected into each machine, such chemicals including different types of detergent, bleaches, and souring agents, and the like. For purposes of economy and efficiency, and to make each washer as versatile as possible, it is preferred to provide that each chemical can be injected into every washer. It is also preferred that single reservoirs be provided for each chemical for the entire laundry, and that a single pump be provided for the delivery of each chemical, the pump generally being capable of delivering that chemical only to one washer at a time. This creates a problem if a particular chemical is demanded by more than one washer at a time. There are other common functions which should be performed by only one washer at a time, in addition to the injection of individual chemicals. For instance, it is very desirable that a high speed spin operation (for extraction) be performed by only one washer at a time so as to keep the peak electrical load demand for the laundry as low as possible.
Accordingly, it is an important object of the invention to provide an improved control system for a multiple washer laundry which is capable of assuring that only one washer at a time performs a common function which is to be performed by only one washer at a time.
2. Description of Prior Art
One very useful approach to the above problem is disclosed in U.S. Pat. No. 3,961,231 issued June 1, 1976 for a "Controlled Chemical Injection System for Washing Machines" invented by the same inventor as the present invention and assigned to the same assignee as the present invention. The system of that patent requires a separate relay interlock system interlinking all of the washing machines for every separate chemical supply system, with separate blocking relay contacts operable by each washer to block out every other washer when that washer is using the common chemical supply system. That system is very useful and has been found to be very satisfactory, except that the number of contact points required by each washer to block every other washer for every common function which is to be performed by only one washer at a time becomes excessive in a larger system, and the amount of wiring required between the controllers for the different washers becomes excessive and complicated.
Accordingly, it is another objective of the present invention to overcome the disadvantages of prior systems of the nature described above, and to provide an improved control and operating system for a laundry which permits only one washer at a time to perform a common function that must be performed by only one washer at a time.